Upgrade all lizard VMs to Jessie

Expected outcome:

(with #11178 (closed)): drop Wheezy special cases from our Puppet code
don’t have to go through Wheezy -> Stretch upgrade (yes, there will be wheezy-lts but I suspect this upgrade path will be less well tested than Wheezy -> Jessie + Jessie -> Stretch)
be able to rely on having systemd everywhere

Original created by @intrigeri on 11186 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information